1. Field of the Invention
The present invention relates to a numerical controller for controlling a plurality of paths, and more particularly to a numerical controller having an axis reconfiguration function between the paths.
2. Description of Related Art
In a multi-path numerical controller having at least two paths, there has been known a technique for moving or exchanging axis control between the paths, to thereby reconfigure axes belonging to the paths for improvement of machining efficiency. This technique is disclosed in, e.g., JP 3199319B.
Another technique relating to a numerical controller has been known, in which axis control right for each individual path is changeably set by a flexible path axis assignment command in a machining program, and an axis-related configuration is stored, which indicates axis addresses of respective paths at the time of flexible path axis assignment being commanded. When a command is given for returning the control right to the path before flexible path axis assignment, the control right is returned to the path before flexible path axis assignment based on the axis-related configuration. This technique is disclosed in JP 10-11120A.
To implement axis exchange between paths, a conventional numerical controller with interpath axis reconfiguration function generates a waiting command (other than the axis exchange command) for relevant paths to create a state where execution of programs is stopped in these path, and executes the axis exchange command in that state to implement axis reconfiguration. Thus, a problem is posed that the machining cycle time is lengthened by the time required for execution of the waiting command. Similarly, when an axis motion command is given, an axis motion process is executed while the waiting command is being implemented in relevant paths, thus posing the problem that the machining cycle time becomes long.
Such machine adapted to implement the axis reconfiguration is mostly applied to a machine for mass production of precise workpieces, which is called automatic machine. In the case of a method for cutting precise workpieces by giving an instruction consisting of a set of a waiting command and an axis reconfiguration command, the waiting command is a redundant command. Specifically, if the waiting command requires 16 msec to complete and the combinatorial command consisting of the waiting command and the axis reconfiguration command is given four times in the program, the dead time of 64 msec is exhausted for each precise workpiece. To cut ten thousand precise workpieces, the dead time of (64 msec×10000 pieces)/1000 msec=640 seconds is exhausted.
The technique disclosed in JP 10-11120A is a technique in which predetermined processing is implemented after exchange of axis control, a state of a flexible path axis assignment inhibition flag, which represents whether axis control exchange can be made upon restoration to the previous axis configuration, is determined, and based on the flag state, the axis exchange is prohibited or waiting is made until the prohibited state is canceled. However, to cancel the prohibited state, another command (i.e., a flexible path axis assignment restoration prohibition canceling command) must be given, which poses a problem that the machining cycle time becomes long and the machining cycle time related to the axis exchange command cannot be shortened.